package com.example.mq.mqserver;

import com.example.mq.common.*;
import com.example.mq.mqserver.core.BasicProperties;
import com.example.mq.mqserver.core.Binding;
import com.example.mq.mqserver.core.Exchange;
import org.springframework.stereotype.Repository;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * 服务器（TCP）
 */
public class BrokerServer {

    private ServerSocket serverSocket = null;

    // 只考虑一个 BrokerServer 上只有一个 虚拟主机
    private VirtualHost virtualHost = new VirtualHost("default");

    // key 是 channelId, value 是对应的 Socket 对象
    private ConcurrentHashMap<String, Socket> sessions = new ConcurrentHashMap<>();

    // 引入一个线程池，来处理多个客户端的请求
    private ExecutorService executorService = null;

    // 控制服务器是否继续运行
    private volatile boolean runnable = true;

    public BrokerServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }

    public void start() throws IOException {
        System.out.println("[BrokerServer] 启动！");
        executorService = Executors.newCachedThreadPool();
        try{
            while(runnable){
                Socket clientSocket = serverSocket.accept();
                // 将处理连接的逻辑丢给这个线程池
                executorService.submit(() -> {
                    processConnection(clientSocket);
                });
            }
        }catch (SocketException e){
            System.out.println("[BrokerServer] 服务器停止运行！");
        }
    }

    // 停止服务器
    public void stop() throws IOException {
        runnable = false;
        // 把线程池中的任务都放弃了，让线程都销毁
        executorService.shutdownNow();
        serverSocket.close();
    }

    // 处理一个客户端的连接
    private void processConnection(Socket clientSocket) {
        try(InputStream inputStream = clientSocket.getInputStream();
            OutputStream outputStream = clientSocket.getOutputStream()){
            // 这里需要特定格式来读取并解析，此时就需要用到 DataInputStream 和 DataOutputStream
            try(DataInputStream dataInputStream = new DataInputStream(inputStream);
                DataOutputStream dataOutputStream = new DataOutputStream(outputStream)){
                while(true){
                    // 1. 读取请求并解析
                    Request request = readRequest(dataInputStream);
                    // 2. 根据请求计算响应
                    Response response = process(request, clientSocket);
                    // 3. 把响应写回给客户端
                    writeReponse(dataOutputStream, response);
                }
            }catch (EOFException | SocketException e){
                System.out.println("[BrokerServer] connection 关闭！刻度段的地址：" + clientSocket.getInetAddress().toString()
                + ":" + clientSocket.getPort());
            }
        }catch(IOException | ClassNotFoundException | MqException e){
            System.out.println("[BrokerServer] connection 出现异常！");
            e.printStackTrace();
        }finally {
            try{
                // 当连接处理完了，关闭
                clientSocket.close();
                // 一个 TCP 连接中，可能包含多个 channel ，需要把当前这个 socket 对应的所有 channel 也顺便清掉
                clearCloseSession(clientSocket);
            }catch (IOException e){
                e.printStackTrace();
            }
        }
    }
    private Request readRequest(DataInputStream dataInputStream) throws IOException {
        Request request = new Request();
        request.setType(dataInputStream.readInt());
        request.setLength(dataInputStream.readInt());
        byte[] payload = new byte[request.getLength()];
        int n = dataInputStream.read(payload);
        if(n != request.getLength()){
            throw new IOException("读取请求格式错误!");
        }
        request.setPayload(payload);
        return request;
    }

    private void writeReponse(DataOutputStream dataOutputStream, Response response) throws IOException {
        dataOutputStream.writeInt(response.getType());
        dataOutputStream.writeInt(response.getLength());
        dataOutputStream.write(response.getPlayload());
        // 刷新缓存区
        dataOutputStream.flush();
    }

    private Response process(Request request, Socket clientSocket) throws IOException, ClassNotFoundException, MqException {
        // 1. 把 request 中的 payload 做一个初步的解析
        BasicArguments basicArguments = (BasicArguments) BinaryTool.fromBytes(request.getPayload());
        System.out.println("[Request] rid = " + basicArguments.getRid() + ", channelId = " + basicArguments.getChannelId()
        + ", type = " + request.getType() + ", length = " + request.getType());
        // 2. 根据 type 的值，来进一步区分接下来这次请求要干嘛
        boolean ok = true;
        if(request.getType() == 0x1){
            // 创建 channel
            sessions.put(basicArguments.getChannelId(), clientSocket);
            System.out.println("[BrokerServer] 创建 channel 完成！ channelId = " + basicArguments.getChannelId());
        }else if(request.getType() == 0x2){
            // 销毁 channel
            sessions.remove(basicArguments.getChannelId(), clientSocket);
            System.out.println("[BrokerServer] 销毁 channel 完成！ channelId = " + basicArguments.getChannelId());
        }else if(request.getType() == 0x3){
            // 创建交换机
            ExchangeDelclareArguments arguments = (ExchangeDelclareArguments) basicArguments;
            ok = virtualHost.exchangeDeclare(arguments.getExchangeName(), arguments.getExchangeType(), arguments.isDurable(),
                    arguments.isAutoDelete(), arguments.getArguments());
        }else if(request.getType() == 0x4){
            // 删除交换机
            ExchangeDeleteArguments arguments = (ExchangeDeleteArguments) basicArguments;
            ok = virtualHost.exchangeDelete(arguments.getExchangeName());
        }else if(request.getType() == 0x5){
            // 创建队列
            QueueDeclareArguments arguments = (QueueDeclareArguments) basicArguments;
            ok = virtualHost.queueDeclare(arguments.getQueueName(), arguments.isDurable(),
                    arguments.isExclusive(), arguments.isAutoDelete(), arguments.getArguments());
        }else if(request.getType() == 0x6){
            // 删除队列
            QueueDeleteArguments arguments = (QueueDeleteArguments) basicArguments;
            ok = virtualHost.queueDelete(arguments.getQueueName());
        }else if(request.getType() == 0x7){
            // 创建绑定
            QueueBindArguments arguments = (QueueBindArguments) basicArguments;
            ok = virtualHost.queueBinding(arguments.getQueueName(), arguments.getExchangeName(), arguments.getBindingKey());
        }else if(request.getType() == 0x8){
            // 删除绑定
            QueueUnbindArguments arguments = (QueueUnbindArguments) basicArguments;
            ok = virtualHost.queueUnBinding(arguments.getExchangeName(), arguments.getQueueName());
        }else if(request.getType() == 0x9){
            // 发送 message
            BasicPublishArguments arguments = (BasicPublishArguments) basicArguments;
            ok = virtualHost.basicPublish(arguments.getExchangeName(), arguments.getRoutingKey(),
                    arguments.getBasicProperties(), arguments.getBody());
        }else if(request.getType() == 0xa){
            // 订阅 message
            BasicConsumeArguments arguments = (BasicConsumeArguments) basicArguments;
            ok = virtualHost.basicConsume(arguments.getConsumerTag(), arguments.getQueueName(), arguments.isAutoAck(),
                    new Consumer() {
                        // 这个回调函数要做的就是把服务器收到的消息可以直接推送回对应的消费者客户端
                        @Override
                public void handleDelivery(String consumerTag, BasicProperties basicProperties, byte[] body) throws MqException, IOException {
                            // 要先知道收到的消息要发往哪个客户端
                            // consumerTag 其实是 channelId , 根据 channelId 去 sessions 中查询，
                            // 可以得到对应的 socket 对象，从而发送数据
                            // 1. 根据 channelId 找到 socket 对象
                            Socket clientSocket = sessions.get(consumerTag);
                            if(null == clientSocket || clientSocket.isClosed()){
                                throw new MqException("[BrokerServer] 订阅消息的客户端已经关闭！");
                            }
                            // 2. 构造响应数据
                            SubScribeReturns subScribeReturns = new SubScribeReturns();
                            subScribeReturns.setChannelId(consumerTag);
                            // 只有响应，没有请求，不需要对应
                            subScribeReturns.setRid("");
                            subScribeReturns.setOk(true);
                            subScribeReturns.setConsumerTag(consumerTag);
                            subScribeReturns.setBasicProperties(basicProperties);
                            subScribeReturns.setBody(body);
                            byte[] payload = BinaryTool.toBytes(subScribeReturns);
                            Response response = new Response();
                            // 0xc 表示服务器给消费者客户端推送的消息数据
                            response.setType(0xc);
                            // response 的 payload 就是一个 SubScribeReturns
                            response.setLength(payload.length);
                            response.setPlayload(payload);
                            // 3. 将数据写回给客户端
                            DataOutputStream dataOutputStream = new DataOutputStream(clientSocket.getOutputStream());
                            writeReponse(dataOutputStream, response);
                }
            });
        }else if(request.getType() == 0xb){
            // 调用 basicAck 确认消息
            BasicAckArguments arguments = (BasicAckArguments) basicArguments;
            ok = virtualHost.basicAck(arguments.getQueueName(), arguments.getMessageId());
        }else{
            // 当前 type 非法
            throw new MqException("[BrokerServer] 未知的 type! type = " + request.getType());
        }
        // 构造响应
        BasicReturns basicReturns = new BasicReturns();
        basicReturns.setChannelId(basicArguments.getChannelId());
        basicReturns.setRid(basicArguments.getRid());
        basicReturns.setOk(ok);

        byte[] payload = BinaryTool.toBytes(basicReturns);
        Response response = new Response();
        response.setType(request.getType());
        response.setLength(payload.length);
        response.setPlayload(payload);
        System.out.println("[Response] rid = " + basicReturns.getRid() + ", channelId = " + basicReturns.getChannelId()
        + ", type = " + response.getType() + ", length = " + response.getLength());
        return response;
    }

    private void clearCloseSession(Socket clientSocket) {
        //遍历上述 sessions 哈希表，把该被关闭的 socket 对应的键值对，删掉
        List<String> toDeleteChannelId = new ArrayList<>();
        for(Map.Entry<String, Socket> entry : sessions.entrySet()){
            if(entry.getValue() == clientSocket){
                // 不能直接在这里删除
                // 集合类中不能一边遍历一边删除
                toDeleteChannelId.add(entry.getKey());
            }
        }
        for(String channelId : toDeleteChannelId){
            sessions.remove(channelId);
        }
        System.out.println("[BrokerServer] 清理 session 完成！被清理的 channelId = " + toDeleteChannelId);
    }
}
